This invention relates in general to modular electronic systems in which individual plug-in module cards having different functions fit into a shelf assembly in an equipment cabinet. The modules may be of different thicknesses depending upon the amount of electronic circuitry contained therein. Typically, the modules have flanges on the top and bottom of their frames, which fit into grooves in shelf plates in the shelf assembly. The shelf plates in the shelf assembly are generally made of metal to provide enough strength to firmly hold the modules in position.
There is a significant reduction in cost if the shelf plates in the shelf assembly could be molded out of plastic or a similar material. However, due to the flexibility of these materials, it is not possible to securely hold the modules in the shelf assembly, especially toward the center of the shelf plate. The present invention overcomes this problem in the prior art.